Problem
For students who firstenrolled in two-year public institutions in a recent semester, the proportion who earned a bachelor's degree within six years was 0.389 . The president of a certain junior college believes that the proportion of students who enroll in her institution have a higher completion rate. (a) State the null and alternative hypotheses in words. (b) State the null and alternative hypotheses symbolically. (c) Explain what it would mean to make a Type I error. (d) Explain what it would mean to make a Type II error. (a) State the null hypothesis in words. Choose the correct answer below. A. Among students who first enroll in two-year public institutions, the completion rate is 0.389 . B. Among students who enroll at the certain junior college, the completion rate is 0.389 . C. Among students who enroll at the certain junior college, the completion rate is greater than 0.389 . D. Among students who enroll at the certain junior college, the completion rate is less than 0.389 .
Solution
Step 1 ：The null hypothesis is a statement of no effect or no difference. It is usually the hypothesis that the researcher is trying to disprove. In this case, the null hypothesis would be that the completion rate at the certain junior college is the same as the average completion rate for two-year public institutions, which is 0.389.
Step 2 ：Therefore, the correct answer is B. Among students who enroll at the certain junior college, the completion rate is 0.389.
Step 3 ：Final Answer: \(\boxed{B}\)
